C# VS2017的.net Core1.0项目在版本升级为2.0后找不到程序集的处理办法

最近不小心升级了VS2017，然后原来的.net web core1.0的项目是引用了DataBaseLib的程序集，如图  ，升级之后安装了2.0的框架，发现项目就报错了，，这个是还是之后报的错误，第一个错误是Unable to find the library 'DataBase.dll',也就是找不到所引用的程序集的位置。借助同事以及stackoverflow等问答网站，整理的解决办法如下：

修改startup.cs中的代码文件：

原来的代码:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;

namespace OneStop
{
    public class Startup
    {
        public Startup(IHostingEnvironment env)
        {
            var builder = new ConfigurationBuilder()
                .SetBasePath(env.ContentRootPath)
                .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
                .AddEnvironmentVariables();
            Configuration = builder.Build();
        }

        public IConfigurationRoot Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            // Add framework services.
            services.AddMvc();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.AddConsole(Configuration.GetSection("Logging"));
            loggerFactory.AddDebug();

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseBrowserLink();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
            }

            app.UseStaticFiles();

            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}

处理之后的代码：

using DataBaseLib;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Features;
using Microsoft.AspNetCore.Mvc;
using Microsoft.DotNet.PlatformAbstractions;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyModel;
using Microsoft.Extensions.DependencyModel.Resolution;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
using System;
using System.Collections.Generic;
using System.IO;
using System.Reflection;

namespace Assemble
{
    public class Startup
    {
        public Startup(IHostingEnvironment env)
        {
            var builder = new ConfigurationBuilder()
                .SetBasePath(env.ContentRootPath)
                .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
                .AddEnvironmentVariables();
            Configuration = builder.Build();
        }

        public IConfigurationRoot Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {


            Initialize.ConfigureServices(services);
            // Add framework services.

            var mvcBuilder = services.AddMvc();
            new MvcConfiguration().ConfigureMvc(mvcBuilder);

        }

        public class MvcConfiguration : IDesignTimeMvcBuilderConfiguration
        {
            private class DirectReferenceAssemblyResolver : ICompilationAssemblyResolver
            {
                public bool TryResolveAssemblyPaths(CompilationLibrary library, List<string> assemblies)
                {
                    if (!string.Equals(library.Type, "reference", StringComparison.OrdinalIgnoreCase))
                    {
                        return false;
                    }

                    var paths = new List<string>();

                    foreach (var assembly in library.Assemblies)
                    {
                        var path = Path.Combine(ApplicationEnvironment.ApplicationBasePath, assembly);

                        if (!File.Exists(path))
                        {
                            return false;
                        }

                        paths.Add(path);
                    }

                    assemblies.AddRange(paths);

                    return true;
                }
            }

            public void ConfigureMvc(IMvcBuilder builder)
            {
                // .NET Core SDK v1 does not pick up reference assemblies so
                // they have to be added for Razor manually. Resolved for
                // SDK v2 by https://github.com/dotnet/sdk/pull/876 OR SO WE THOUGHT
                /*builder.AddRazorOptions(razor =>
                {
                razor.AdditionalCompilationReferences.Add(
                MetadataReference.CreateFromFile(
                typeof(PdfHttpHandler).Assembly.Location));
                });*/

                // .NET Core SDK v2 does not resolve reference assemblies‘ paths
                // at all, so we have to hack around with reflection
                typeof(CompilationLibrary)
                .GetTypeInfo()
                .GetDeclaredField("<DefaultResolver>k__BackingField")
                .SetValue(null, new CompositeCompilationAssemblyResolver(new ICompilationAssemblyResolver[]
                {
                    new DirectReferenceAssemblyResolver(),
                    new AppBaseCompilationAssemblyResolver(),
                    new ReferenceAssemblyPathResolver(),
                    new PackageCompilationAssemblyResolver(),
                }));
            }
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.AddConsole(Configuration.GetSection("Logging"));
            loggerFactory.AddDebug();

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseBrowserLink();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
            }

            app.UseStaticFiles();

            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Solution}/{action=Index}/{id?}");
            });
        }
    }

}

希望能对大家有所帮助！